1. Field of the Invention
The present invention relates to a method of and an apparatus for displaying halftone images in frames each divided into subframes, and more particularly, to a method of and an apparatus for displaying halftone images on a gas discharge display panel without halftone disturbance or false color contours.
2. Description of the Related Art
Recently, in order to meet a demand for large thin display units, matrix display panels that display images based on digital signals have been developed. The matrix display panels include gas discharge panels, DMDs (digital micromirror devices), EL (electro luminescence) display panels, fluorescent display panels, and liquid crystal display panels. Among them, the gas discharge panels such as plasma display panels are considered to be most advantageous for direct-view large HDTV (high-quality television) displays because they are simple and easy to form as a large screen, emit light by themselves, provide high display quality, and achieve high-speed response.
A memory-type gas discharge panel displays a halftone image in frames, and the frames are generated at a frequency of, for example, 60 Hz, and each frame consists of N subframes to provide intensity levels 20 to 2Nxe2x88x921. The subframes of each frame are turned on/off, and the human eye sees the sum of the intensity levels of the ON subframes as the intensity level of the frame due to the persistence characteristic of the human eye. The number of intensity levels realized in each frame with combinations of the subframes is 2N.
Note that, if frames that represent similar intensity levels with quite different combinations of ON subframes alternate, flicker will occur to deteriorate display quality. Further, although the subframes of each frame actually emit light from a single pixel, to the human eye it appears as if they emit light from different pixels when a dynamic image is displayed. In this case, an intensity level assigned to a given frame is not displayed as the sum of the subframes, thereby causing halftone disturbance.
By the way, in the related art, a method of, and an apparatus for, displaying halftone images by adding a corrective pulse that turns on or off a corresponding subframe to adjust an intensity level is proposed. This related art is advantageous in that it realizes a given intensity level on the human eye, and thus the halftone image is visible without disturbance if it is seen away from the display. Namely, the related art is effective to stabilize still and moving images. However, it is unsatisfactory on fast-moving images.
The prior and related arts, and their associated problems, will be described in detailed later with reference to the accompanying drawings.
It is an object of the present invention to provide a method of, and an apparatus for, correctly displaying fast-moving halftone images on a screen without halftone disturbance or false color contours.
According to the present invention, there is provided a method of displaying a dynamic halftone image on a display panel made of pixels by dividing each frame of the image into subframes and by turning on and off the subframes, comprising the steps of finding a line of pixels that simultaneously display a specific intensity level in a frame and another specific intensity level in the next frame; counting the number of pixels in the line; selecting corrective pulses, which turn on/off corresponding subframes to enable/disable corresponding intensity levels, according to the counted number and a change in the specific intensity levels between the frames; and adjusting original display signals for the pixels in the line according to the corrective pulses, respectively.
Further, according to the present invention, there is provided a method of displaying a dynamic halftone image on a display panel made of pixels by dividing each frame of the image into subframes and by turning on and off the subframes, comprising the steps of finding a line of pixels that simultaneously display a specific intensity level in a frame and another specific intensity level in the next frame; counting the number of pixels in the line; detecting the statuses of two adjacent pixels on each side of the line of pixels in the frames; selecting corrective pulses, which turn on/off, corresponding subframes to enable/disable corresponding intensity levels, according to the statuses of the adjacent pixels, the counted number, and a change in the specific intensity levels between the frames; and adjusting original display signals for the pixels in the line according to the corrective pulses, respectively.
In addition, according to the present invention, there is provided a method of displaying a dynamic halftone image on a display panel made of pixels by dividing each frame of the image into subframes and by turning on and off the subframes, comprising the steps of finding, in each of the vertical and horizontal directions, a line of pixels that simultaneously display a specific intensity level in a frame and another specific intensity level in the next frame; counting the number of pixels in each of the lines; selecting corrective pulses, which turn on/off corresponding subframes to enable/disable corresponding intensity levels, according to a smaller one of the counted numbers and a change in the specific intensity levels between the frames; and adjusting original display signals for the pixels of the smaller number according to the corrective pulses, respectively.
According to the present invention, there is also provided a method of displaying a dynamic halftone image on a display panel made of pixels by dividing each frame of the image into subframes and by turning on and off the subframes, comprising the steps of finding, in each of vertical and horizontal directions, a line of pixels that simultaneously display a specific intensity level in a frame and another specific intensity level in the next frame; counting the number of pixels in each of the lines; detecting the statuses of two adjacent pixels on each side of each of the lines in the frames; selecting corrective pulses, which turn on/off corresponding subframes to enable/disable corresponding intensity levels, according to a smaller one of the counted numbers with the two adjacent pixels having different statuses and a change in the specific intensity levels between the frames; and adjusting original display signals for the pixels of the smaller number according to the corrective pulses, respectively.
Further, according to the present invention, there is also provided a method of displaying a dynamic halftone image on a display panel made of pixels by dividing each frame of the image into subframes and by turning on and off the subframes, comprising the steps of finding, in each of vertical and horizontal directions, a line of pixels that simultaneously display a specific intensity level in a frame and another specific intensity level in the next frame; counting the number of pixels in each of the lines; detecting the statuses of two adjacent pixels on each side of each of the lines in the frames; selecting corrective pulses, which turn on/off corresponding subframes to enable/disable corresponding intensity levels, according to a smaller one of the counted numbers if the statuses of the two adjacent pixels of any one of the lines are equal to each other, and according to a change in the specific intensity levels between the frames; and adjusting original display signals for the pixels of the smaller number according to the corrective pulses, respectively.
In addition, according to the present invention, there is also provided a method of displaying a dynamic halftone image on a display panel made of pixels by dividing each frame of the image into subframes and by turning on and off the subframes, comprising the steps of finding, in each of the vertical and horizontal directions, a line of pixels that simultaneously display a specific intensity level in a frame and another specific intensity level in the next frame; counting the number of pixels in each of the lines; detecting the statuses of two adjacent pixels on each side of each of the lines in the frames; selecting corrective pulses, which turn on/off corresponding subframes to enable/disable corresponding intensity levels, according to one of the counted numbers with the two adjacent pixels having different statuses and a change in the specific intensity levels between the frames; and adjusting original display signals for the pixels in the line with the two adjacent pixels having different statuses according to the corrective pulses, respectively.
The original display signals may be adjusted according to the corrective pulses only when the two adjacent pixels of the line in question have different statuses. The corrective pulses may be zeroed when the two adjacent pixels of the line in question are equal to each other. At least one of the original display signals may be adjusted according to the corrective pulses when the two adjacent pixels of the line in question are equal to each other.
According to the present invention, there is provided a method of displaying a dynamic halftone image on a display panel made of pixels by dividing each frame of the image into subframes and by turning on and off the subframes, comprising the steps of finding a line of pixels that simultaneously display a specific intensity level in a frame and another specific intensity level in the next frame; selecting identical or different corrective pulses, which turn on/off corresponding subframes to enable/disable corresponding intensity levels, according to the line of pixels; and adjusting original display signals for the pixels in the line according to the corrective pulses, respectively.
Further, according to the present invention, there is provided a method of displaying a dynamic halftone image on a display panel made of pixels by dividing each frame of the image into subframes and by turning on and off the subframes, comprising the steps of finding a line of pixels that simultaneously display a specific intensity level in a frame and another specific intensity level in the next frame; preparing corrective pulses corresponding to sequentially increasing or decreasing intensity levels according to the line of pixels; and adjusting original display signals for the pixels in the line according to the corrective pulses, respectively.
In addition, according to the present invention, there is provided a method of displaying a dynamic halftone image on a display panel made of pixels by dividing each frame of the image into subframes and by turning on and off the subframes, comprising the steps of finding a line of n pixels that simultaneously display a specific intensity level in a frame and another specific intensity level in the next frame; calculating the sum xcex94S of stimulus (stimuli) on the retina to be produced with a corrective pulse, which will be applied to one of the n pixels, as follows:
B1Txe2x89xa6B2T+xcex94Sxe2x89xa6B3T, or 
B1Txe2x89xa7B2T+xcex94Sxe2x89xa7B3T 
where T is a period in which the intensity level of the n pixels changes from one to another, B1 is an average of stimulus (stimuli) on the retina due to one of the n pixels before the change, B2 is an average of stimulus on the retina due to the same during the change, and B3 is an average of stimulus on the retina due to the same after the change; selecting identical or different corrective pulses, which turn on/off corresponding subframes to enable/disable corresponding intensity levels, so that the total sum of stimulus on the retina to be produced with the corrective pulses is substantially equal to nxcex94S; and adjusting original display signals for the n pixels according to the corrective pulses, respectively.
Further, according to the present invention, there is provided a method of displaying a dynamic halftone image on a display panel made of pixels by dividing each frame of the image into subframes and by turning on and off the subframes, comprising the steps of finding a line of n pixels that simultaneously display a specific intensity level in a frame and another specific intensity level in the next frame; calculating the sum xcex94S of stimulus on the retina to be produced with an corrective pulse, which will be applied to one of the n pixels, as follows:
if B2xe2x89xa6(B1+B3)/2 then 0xe2x89xa6xcex94Sxe2x89xa6(B1+B3xe2x88x922B2)T 
if B2xe2x89xa7(B1+B3)/2 then 0xe2x89xa7xcex94Sxe2x89xa7(B1+B3xe2x88x922B2)T 
where T is a period in which the intensity level of the n pixels changes from one to another, B1 is an average of stimulus on the retina due to one of the n pixels before the change, B2 is an average of stimulus on the retina due to the same during the change, and B3 is an average of stimulus on the retina due to the same after the change; selecting identical or different corrective pulses, which turn on/off corresponding subframes to enable/disable corresponding intensity levels, so that the total sum of stimulus on the retina to be produced with the corrective pulses is substantially equal to nxcex94S; and adjusting original display signals for the n pixels according to the corrective pulses, respectively.
According to the present invention, there is also provided a method of displaying a dynamic halftone image on a display panel made of pixels by dividing each frame of the image into subframes and by turning on and off the subframes, comprising the steps of finding a plurality of pixels that simultaneously display an intensity level in a frame and another intensity level in the next frame; comparing the intensity levels with each other; selecting weighted corrective pulses, which turn on/off corresponding subframes to enable/disable corresponding intensity levels, according to the number of the found pixels and a change in the intensity levels between the frames; and adjusting original display signals for the found pixels according to the corrective pulses, respectively.
Each of the pixels may consist of three subpixels for emitting three primary colors of red, green, and blue, respectively, the subpixels being combined to display a color.
According to the present invention, there is provided a display apparatus for displaying a dynamic halftone image on a display panel made of pixels by dividing each frame of the image into subframes and by turning on and off the subframes, comprising a finding unit for finding a line of pixels that simultaneously display a specific intensity level in a frame and another specific intensity level in the next frame; a counting unit for counting the number of pixels in the line; a selecting unit for selecting corrective pulses, which turn on/off corresponding subframes to enable/disable corresponding intensity levels, according to the counted number and a change in the specific intensity levels between the frames; and an adjusting unit for adjusting original display signals for the pixels in the line according to the corrective pulses, respectively.
Further, according to the present invention, there is provided a display apparatus for displaying a dynamic halftone image on a display panel made of pixels by dividing each frame of the image into subframes and by turning on and off the subframes, comprising a finding unit for finding, in each of vertical and horizontal directions, a line of pixels that simultaneously display a specific intensity level in a frame and another specific intensity level in the next frame; a first counting unit for counting the number of pixels in the horizontal line; a second counting unit for counting the number of pixels in the vertical line; a detecting unit for detecting the statuses of two adjacent pixels on each side of each of the horizontal and vertical lines in the frames; a first selecting unit for selecting one of the horizontal and vertical lines according to the counted numbers and the statuses of the adjacent pixels; a second selecting unit for selecting corrective pulses, which turn on/off corresponding subframes to enable/disable corresponding intensity levels, according to the number of pixels in the selected line and the statuses of the two adjacent pixels of the selected line; and an adjusting unit for adjusting original display signals for the pixels in the selected line according to the corrective pulses, respectively.
The original display signals may be adjusted according to the corrective pulses only when the two adjacent pixels of the line in question have different statuses. The corrective pulses may be zeroed when the two adjacent pixels of the line in question are equal to each other. At least one of the original display signals may be adjusted according to the corrective pulses when the two adjacent pixels of the line in question are equal to each other.
In addition, according to the present invention, there is provided a display apparatus for displaying a dynamic halftone image on a display panel made of pixels by dividing each frame of the image into subframes and by turning on and off the subframes, comprising a finding unit for finding a plurality of pixels that simultaneously display an intensity level in a frame and another intensity level in the next frame; a comparing unit for comparing the intensity level with each other; a selecting unit for selecting weighted corrective pulses, which turn on/off corresponding subframes to enable/disable corresponding intensity levels, according to the number of the found pixels, the statuses of adjacent pixels on each side of the found pixels in the frames, and a change in the intensity levels between the frames; and an adjusting unit for adjusting original display signals for the found pixels according to the corrective pulses, respectively.
Each of the pixels may consist of three subpixels for emitting three primary colors of red, green, and blue, respectively, the subpixels being combined to display a color.
According to the present invention, there is also provided a medium for storing a computer program for displaying a dynamic halftone image on a display panel made of pixels by dividing each frame of the image into subframes and by turning on and off the subframes, the program comprising the steps of finding a line of pixels that simultaneously display a specific intensity level in a frame and another specific intensity level in the next frame; counting the number of pixels in the line; selecting corrective pulses, which turn on/off corresponding subframes to enable/disable corresponding intensity levels, according to the counted number and a change in the specific intensity levels between the frames; and adjusting original display signals for the pixels in the line according to the corrective pulses, respectively.
Further, according to the present invention, there is also provided a medium for storing a computer program for displaying a dynamic halftone image on a display panel made of pixels by dividing each frame of the image into subframes and by turning on and off the subframes, the program comprising the steps of finding a line of pixels that simultaneously display a specific intensity level in a frame and another specific intensity level in the next frame; counting the number of pixels in the line; detecting the statuses of two adjacent pixels on each side of the line of pixels in the frames; selecting corrective pulses, which turn on/off corresponding subframes to enable/disable corresponding intensity levels, according to the statuses of the adjacent pixels, the counted number, and a change in the specific intensity levels between the frames; and adjusting original display signals for the pixels in the line according to the corrective pulses, respectively.
In addition, according to the present invention, there is also provided a medium for storing a computer program for displaying a dynamic halftone image on a display panel made of pixels by dividing each frame of the image into subframes and by turning on and off the subframes, the program comprising the steps of finding, in each of vertical and horizontal directions, a line of pixels that simultaneously display a specific intensity level in a frame and another specific intensity level in the next frame; counting the number of pixels in each of the lines; selecting corrective pulses, which turn on/off corresponding subframes to enable/disable corresponding intensity levels, according to a smaller one of the counted numbers and a change in the specific intensity levels between the frames; and adjusting original display signals for the pixels of the smaller number according to the corrective pulses, respectively.
Furthermore, according to the present invention, there is also provided a medium for storing a computer program for displaying a dynamic halftone image on a display panel made of pixels by dividing each frame of the image into subframes and by turning on and off the subframes, the program comprising the steps of finding, in each of the vertical and horizontal directions, a line of pixels that simultaneously display a specific intensity level in a frame and another specific intensity level in the next frame; counting the number of pixels in each of the lines; detecting the statuses of two adjacent pixels on each side of each of the lines in the frames; selecting corrective pulses, which turn on/off corresponding subframes to enable/disable corresponding intensity levels, according to a smaller one of the counted numbers with the two adjacent pixels having different statuses and a change in the specific intensity levels between the frames; and adjusting original display signals for the pixels of the smaller number according to the corrective pulses, respectively.